• Journal of the Korean Physical Society
• /
• v.80
• /
• pp.640-646
• /
• 2022

Hybrid PET/MRI is a useful imaging system that can improve diagnostic accuracy by providing both functional and anatomical information. However, the combination of PET and MRI can lead to mutual interference, which can degrade the performances of both imaging systems. One of the methods that is capable of preserving the performance of both modalities is to apply RF shielding to PET detectors and electronics. The purpose of this study was to propose a new RF shielding method using Au-plated conductive fabric (PCF) tape that could not only minimize RF interference and eddy current, but that could also be applied to complex PET gantry and detector module structures more easily than thin Cu foils, which have been widely used as a shielding material for hybrid PET/MRI systems. To evaluate the performance of the proposed new RF shielding method, the effects of the two RF shield materials (Cu and Au) on the B1 + field generated by the RF head coil were estimated using a computer simulation method. The effects of the Au PCF tape and Cu foil on the homogeneity and SNR of the MR image were also experimentally evaluated using a commercial 3-T MRI. The uniformity of the B1 + field map was slightly decreased by the use of Cu and Au RF shields. The deterioration in the MR image quality caused by the Au PCF tape was less than that caused by Cu foil. The simulation and experimental results indicate that Au PCF tape can serve as an alternative shielding material that reduces RF interference and eddy current for hybrid PET/MRI systems.

• Proceedings of the IEEK Conference
• /
• 2001.06a
• /
• pp.413-416
• /
• 2001

In high frequency range, RF circuit design without considering shielding effect can cause several significant changes due to increase in parasitic capacitance and inductance between RF signal lines and shielding box. In this paper, bandpass filter has been made to measure the shielding effect and its s-parameter has been measured by Vector Network Analyzer (VNA). Equivalent circuit model including the shielding effect has been constructed with the lumped elements extracted from the 3D electromagnetic simulator, Maxwell SI. Then, the validity of the model is verified using microwave circuit simulator, ADS (Advanced Design System).

• Proceedings of the KIEE Conference
• /
• 1994.11a
• /
• pp.212-214
• /
• 1994

At recent time, superconducting technology makes it possible to develop various devices using strong magnetic fields. As increasing with devices using high magnetic fields, magnetic shielding technology is essential in order to get high efficiency. Therefore it is necessary to establish production method and clear characteristics of suitable shielding materials. Usually, ferromagnetic metal has been used for shielding of high magnetic fields up to the present time. Instead of heavy ferromagnetic metal, we can acquire better upgraded shielding system by using of very light superconducting thin film that has a perfect diamagnetism. We would like to study basic characteristics of NbTi thin film produced by RF sputtering, investigated morphology and crystal structure of NbTi thin film by SEM and XRD, identified superconductivity measuring by critical current.

• Journal of the Microelectronics and Packaging Society
• /
• v.11 no.3 s.32
• /
• pp.31-36
• /
• 2004

We charaterized electromagnetic shielding properties of a soft magnetic film using by a ASTM method and 2-port flanged coaxial line method in a RF range and quantitatively analyzed factors for the shielding effectiveness of the soft magnetic film in far field. The shielding effectiveness of the soft magnetic film was dominantly affected by absorption loss not reflection loss in high frequency range of 4-13.5 GHz.

• Journal of Aerospace System Engineering
• /
• v.16 no.6
• /
• pp.18-23
• /
• 2022

This paper examines the electromagnetic shielding structure of ultra-high frequency (UHF) RF modules used in aircraft. Advances in electrical and electronic technologies have increased the need for electronic equipment in aircraft. High-frequency wireless devices have become integrated circuits in the form of UHF integrated circuits to support a wide range of frequencies and miniaturisation. To ensure the functionality and performance of these integrated devices in aviation, shielding is necessary to prevent unexpected electromagnetic interference, which could be detrimental to aircraft safety. A shield structure was designed to protect the RF chipset from malfunctioning, and the shielding effectiveness was improved through the application of various geometric shapes.

• Korean Journal of Materials Research
• /
• v.9 no.11
• /
• pp.1055-1061
• /
• 1999

Indium Tin Oxide (ITO) films were fabricated by vacuum deposition technique and their microwave shielding properties were investigated for the application to the transparent shield material. The vacuum coating was conducted in a RF co-sputtering machine. The film composition and structure associated with the sputtering conditions (argon and oxygen pressure. substrate temperature. RF input power) were investigated for the attainment of high electrical conductivity and good transparency. The electrical conductivity of IT0 films fabricated under the optimum deposition conditions (substrate temperature : $300^{\circ}C$. Ar flow rate : 20 sccm, Oxygen flow rate : 10 sccm, In/Sn input power : 50/30 W) showed 5.6$\times10^4$mho/m. The optical transparency is also considerably good. The microwave shielding properties including the dominant shielding mechanism are investigated from the electrical conductivity, thickness and skin depth of the ITO films. The total shielding effectiveness is then estimated to be 26 dB, which provides a suggestion that the IT0 films can be effectively used as the transparent shield material.

• Proceedings of the IEEK Conference
• /
• 2009.05a
• /
• pp.350-353
• /
• 2009

The shielding enclosure is very essential device to test the electromagnetic wave power generated by various RF equipments. Some standards for the shielding enclosures were established to test them in right method. Generally, There are IEEE-STD-299 and MIL-STD-285 and NSA-65-6 of the method for measuring the effectiveness of shielding enclosures, the IEEE-STD-299 combined MIL-STD-285 and NSA-65-6 about the method for measuring shielding effectiveness(SE) about 1969 years, but, the measurement point of 299 proposal is many points(including shielding wall, seam, coner beat, shielding door, etc) and demand long time of measurement. To improve SE test method for shielding enclosures was studied and suggested to develop a proper test procedure. First, we measure reference level as frequency range and H/V polarization, secondly, measure leakage point, and finally, measure shield effect and calculate SE. Our method has a merit of the less measurement point than IEEE-STD-299, and shorten time than 299, and define representation SE of shielding enclosure effectively.

• The Journal of the Korea Contents Association
• /
• v.21 no.2
• /
• pp.431-436
• /
• 2021

In this study, a new shielding method was applied to an accessory device that produces electromagnetic waves in the magnetic resonance room to prevent the generation of artifact caused by electromagnetic waves. The research method applied a new shielding made of metal plating fiber to patient surveillance CCTVs without shielding technology, and obtained and evaluated noise map when the power was not cut off and when the new shielding technology was applied without shutting down the CCTV. As a result of the study, it was found that there was at least one group with significant differences. Type I and type III belonged to group 1 while type II belonged to group 2 in the Post-hoc analysis, which meant blocking power of the CCTV and the applying new shielding technology were in the same group. In conclusion, if electromagnetic waves are generated due to additional accessories in the scanning room, the shielding material proposed in this study should be applied which enables the electric state become similar to type I, not generating noise, thereby preventing the artifacts caused by electromagnetic waves.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
• /
• v.4 no.3
• /
• pp.45-53
• /
• 1993

The shielding effectiveness of materials is determined by measuring the ratio of the incident electromagnetic power to that which passes through the material under test. The measurement system is constructed using several test fixtures, tracking generator, spectrum analyzer, step attenuator, RF switches, and amplifiers, etc.. The automation of measurements is completed using a personal computer. Especially, incident power, reflected power, and transmitted power are measured with only one spectrum analyzer using a dual directional coupler and RF switches. Therefore the system is to be used in design of shielding materials, as well as shielding effectiveness measurements. This system has dynamic range of more than 120 dB in the frequency range of 10 MHz to 1 GHz, and it can be used to measure shielding effectiveness of composite materials.

• Proceedings of the Korea Contents Association Conference
• /
• 2017.05a
• /
• pp.111-112
• /
• 2017

MRI는 부분 영역을 자세히 영상화하는 검사임에도 인체에 위해한 RF를 전신에 주고 있다. 이러한 문제점을 개선하기 위해 저자들은 RF차단 방호복을 자제제작하여 적용한 결과 적용 전보다 적용 후가 95% 이상 RF를 차단하였다. 따라서 MRI 검사 시 본 연구의 방호복이 인체의 위해를 줄일 수 있는 최적의 대안임을 알 수 있다.